ok now I found out what I did. 1. create map with Mapgenerator v7 2. open map, fly to above +100, close map, close Minetest (use "F5" and "/grant singleplayer all") 3. goto world folder delete "map.sqlite" 4. open map_meta.txt, edit "water_level = 100" 5. start Minetest, open map May not be really ...